CSU Fisheries Ecology
Laboratory
Forensic Applications of Otolith Microchemistry for Tracing
Sources of Illegally Stocked Fishes
Funded by: Whirling Disease Initiative, Montana Water Center
2004-2006
Students and Postdocs
Dan Gibson-Reinemer
Collaborators
Patrick Martinez, Colorado Division of Wildlife
Dana Winkelman, Colorado Cooperative Fish and Wildlife Research Unit, Colorado
State University
Alan Koenig, USGS Mineral Resources Laboratory, Lakewood, CO
Gregory Whitledge, Department of Zoology, Southern Illinois
University
Project Summary
One of the continued threats to viable trout populations in the Mountain
West is the spread of whirling disease via illegal stocking of diseased
trout. Attempts to halt such introductions and prosecute violators have
been thwarted because it has been virtually impossible to trace the origins of
a diseased trout once it has been stocked. Naturally occurring chemical
markers in fish tissue have shown promise as a method to track the origins of
fish in previous studies. However, research to date had not looked at the
potential for these markers to work adequately in hatchery environments over
large areas or to distinguish many potential source hatcheries. We
evaluated the use of chemical markers in fish otoliths, or “ear stones,” to
determine the hatchery of origin of stocked trout.
We found that otolith markers could be highly effective markers of the past
environmental history of trout. We sampled 11 hatcheries and several
populations of stocked trout captured from public waters, simulating conditions
that may occur in a forensic case. Our ability to correctly identify the
hatchery the fish came from increased with the number of chemical markers used
(and hence cost) and when there were fewer “suspect” hatcheries.
Otoliths are capable of providing information about the location a fish has
inhabited, a feat not achievable with any other technique. The
information from otoliths is best used to fill gaps in cases where traditional
methods of investigation have been adequately conducted. The result of this
research will provide law enforcement with a valuable tool to prosecute those
who have illegally stocked trout and serve as a deterrent to future illegal
stockings. Thus, we have provided a useful tool to help preserve the
biological and economic health of trout fisheries.
FINAL
REPORT (pdf)
Dr. Brett M. Johnson
Department of Fish, Wildlife and Conservation Biology
1474 Campus Delivery, Colorado State University,
Fort Collins, CO 80523-1474
voice: 970-491-5002, fax: 970-491-5091
email:
brett.johnson"at"colostate.edu (replace “at” with @)
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